This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Wells are generally drilled into the ground to recover natural deposits of hydrocarbons and other desirable materials trapped in geological formations in the Earth's crust. A well is typically drilled using a drill bit attached to the lower end of a drill string. The well is drilled so that it penetrates the subsurface formations containing the trapped materials and the materials can be recovered.
A variety of valves are used to control flow of actuating fluids in many well applications and other flow control applications. For example, valves are employed in wellbore drilling to control the actuation of tools located in the wellbore being drilled. During wellbore drilling operations, valves positioned in the downhole drilling assembly can be actuated to control the direction of drilling. The valves may be positioned, for example to control the flow of drilling mud to actuating pads which are extended and contracted in a controlled manner to steer the drill bit in the desired direction. In some applications a valve, or valve-type member is actuated to repeatedly interrupt the flow of the drilling fluid to cause varying pressure waves to be generated in the drilling fluid at a carrier frequency to provide signal communication between downhole systems and with the surface. It is desired to know the rotational speed of this valve members and whether or not the device has become blocked due to solids in the drilling fluid. Other factors such as wear, breakage, position of the valve member and the like also contribute to the efficiency of the tool.